# Normal force

The push a surface gives back, at right angles to it, when something presses on it. It changes with acceleration.

Physics (university) · Part 02: Newton's laws and forces · Card 6 of 10 · Last updated 2026-10-19

## Analogy

The floor pushing up on your feet.

## Example

**Elevator rider**

N - mg = ma
N = 70(9.8 + 2)
N = 826 N

## In practice

In an elevator accelerating up at 2 m/s squared, a 70 kg rider feels 826 N from the floor.

## Practice

### Flashcards

- **What is the formula for maximum static friction?** f max = (coefficient of friction) x (normal force).

## Questions people ask

### Is the normal force always equal to weight?

No. It equals weight only when the surface is flat and nothing else pushes vertically or accelerates the object. On a slope it is smaller, and in an accelerating elevator it changes. Always find it from F = ma along the perpendicular direction.

### Why is it called normal?

In maths, normal means at right angles. The normal force is the contact force that acts perpendicular to the surface. It is a push, never a pull, and it stops objects from passing through the surface. It has nothing to do with being ordinary.

## Related concepts

- [Friction](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-7)
- [Newton's first law](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-1)
- [Net force](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-2)
- [Newton's second law](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-3)

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